On Friday 16 September 2016 12:06:47 Chris Albertson wrote:

> Gene,
>
> That was a good data point:  " 60IPS".   May I ask about the lead
> screw and if you are micro stepping?  And the motor size.

Lead screw is a 1605, 40 tooth gear on the motor by way of a taperloc hub 
I made, ditto for the 80 tooth gear on the screw, so the motor is 
running 2x the speed of the screw.  The motor is running on a 39 volt 
power supply, with a 2M542 driver set for 16x microstepping. Motor is an 
8 wire 432 oz/in, wired in series. I am useing a similar if not 
identical, direct drive on the smaller x screw, wired parallel. It 
doesn't move very far, maybe 4" total, but its speed for in and out 
running a g76 threading routine is way more than enough.

When asking steppers to run at those speeds, I think 2 things are 
demanded:

1. No opto-isolators allowed on the breakout board as they can play hell 
with the step timing due to their turn-off lag.  The good drivers all 
have their own and are much better matched in terms of speed.

2. Step rates in that neighborhood can only be generated by an io card 
like the 5i25, or the function generator on yonder test gear shelf.  The 
opto's in the drivers seem to peter out between 300 kilohertz and 350 
kilohertz. With the motor supply at 40 volts, laying on the table, I 
once left an 8 wire motor, running in series coils, spinning an even 
3000 rpms while I came in the house and fixed us both some dinner. It 
was cooler than I expected, but still running a hair over an hour later.

Pulling a screw and moving a machine, that same motor is pretty well 
nailed to the wall at 1000 rpms. PSU voltage is fairly important, the 
more the merrier up to about 80% of the drivers ratings. Even a 12 volt 
supply can get full torque out of the motor, but crank up the revs and 
nothing can maintain that torque to usable speeds but voltage, needed to 
overcome the coil inductance in big, high torque motors that run on 
economical currents.
> I think I'm going to design for a target speed of 100 IPS but if it
> comes out 60 I'll be happy.
>
> On Thu, Sep 15, 2016 at 11:55 AM, Gene Heskett <ghesk...@shentel.net> 
wrote:
> > On Thursday 15 September 2016 12:16:45 Chris Albertson wrote:
> > > Hello,
> > >
> > > Got a "new" computer I saved from going to the dump.  II am going
> > > to it use for LinuxCNC.  I tested latency for a good 30 minutes
> > > and got just under 30,000 over 20,000 on the display.   The PC is
> > > an Intel i7, 2.67 GHz, 4GB RAM and no built-in graphics on the
> > > mother board.  There is a video card in one of the slots.  One PCI
> > > slot is free.
> > >
> > > I want to run some NEMA 23 stepper motors to control a Sieg X2
> > > mill. (aka "Mini Mill".)  Yes, call it a "toy" but the parts I
> > > want to make would fit on your open hand.  I have a rotary table I
> > > am converting also and hope one day to be able to do 4-axis work.
> > >
> > > Questions:
> > >
> > > 1)  Is it worth it to experiment with different video drivers and
> > > such to reduce the latency?  The numbers look good enough already,
> > > I think.
> >
> > Not for moving steppers at usable speeds.
> >
> > > 2)  What would I gain by using a Mesa card over a parallel port
> > > card? I don't have either one of these now and would need to buy
> > > one or the other and with only one PCI slot I can use only one
> > > card.
> >
> > A mesa 5i25 with a 10 dollar breakput board on the other end of a
> > parport cable essentially removes the boxes latency from the
> > equation because all you will need is the much slower servo-thread.
> > I still have one software stepper driven machine, and its slow, and
> > z now misses pulses at a maxvel it was happy with at ubu8.04 LTS. 
> > So I intend to put one of the 5i25's in it before too long. Its in a
> > box on the floor beside this chair right now. I have the exact same
> > motor on my toy lathe, and with a 5i25 issuing the marching orders
> > it can do 60 ipm without losing a step. The software stepping
> > machine is an identical  intel D-525-MW, but no 5i25. 8 ipm is the
> > speed limit if I don't want it to lose steps.  Thats a huge
> > difference. Best dollars you will spend.
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > Genes Web page <http://geneslinuxbox.net:6309/gene>
> >
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> > Emc-users@lists.sourceforge.net
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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